Certain fasteners include a cylindrical sleeve which is fitted through an opening in a workpiece. The end of the sleeve then is flared outwardly to form a flange used in holding the fastener to the workpiece. Also included may be a rotation-resisting means, such as a straight knurl, which becomes embedded in the wall of the opening when the sleeve is fitted into the opening. This kind of fastener is exemplified by that of U.S. Pat. No. 3,695,324. Fasteners of these types are in widespread use in the aerospace industry.
It is important to have a portable, manually operable tool for installing these fasteners on panels in field service conditions. A successful tool of this nature is shown in U.S. Pat. No. 3,665,581. The tool of this patent includes a puller which is moved by a member within a body, which is actuated by a movable handle. The puller is at the axis of a die member which flares the end of the sleeve of the fastener as the fastener is pulled into the opening in the workpiece. For use with a fastener of the type of U.S. Pat. No. 3,695,324, a two-stage operation is required, first pulling the sleeve into the opening in the workpiece, causing the straight knurl on the fastener sleeve to become embedded in the wall of the opening. After that, the end of the sleeve is bent outwardly by the die surface to form a flange. In the tool of U.S. Pat. No. 3,665,581, a spacer is provided to bear against the workpiece and maintain the die away from the end of the sleeve as the sleeve is drawn into the opening. This is a rotatable member with a C-shaped end, having an opening that enables it to fit around the die member.
This construction has certain disadvantages. In particular, it is not usable for installing the fasteners in thin panels. This is because the spacers does not engage the workpiece around the perimeter of the opening through it, leaving portions of the workpiece unsupported. As a result, a thin panel will buckle as the puller draws the sleeve into the opening in the workpiece against the resistance of the knurl as it becomes embedded in the wall of the workpiece. Also, this prior tool lacks convenience in some respects. Different lengths of pullers must be installed in order to accommodate panels of different thicknesses so that the die surface will be properly located with respect to the end of the sleeve. Replacement of the puller in this tool required disassembly of the major portion of the tool, which is a very time-consuming operation. Also, when the tool of U.S. Pat. No. 3,665,581 is used, there is no assurance that the sleeve will be properly centered with respect to the die surface. This occurs because the nut of the fastener can float relative to the basket upon which it is fitted, enabling it to move laterally to one side, out of alignment with the sleeve. Inasmuch as the puller is attached to the nut, the die of the tool then becomes misaligned with respect to the fastener sleeve. In that event, a proper flare may not be obtained, and, in some instances, the narrow tapering die surface will be broken so as to require an expensive die replacement.